Inductance of Coils

[Leslie]

Here too they have a simulator based on inductance, it seem a little off with the speed and I need to really turn the volts down to match mine.

http://ebikes.ca/simulator/

The green line (efficiency) is whats important to me.  The more turns the slower the motor, but the torque is higher at the slower speeds.

Thinking about it now I wont be able to fit another turn onto these poles and will just try to make it tighter and better.

[Electrobent]

OK, I have a really stupid question:

How did you get the stator out of the hub?

When my 36V died and we tried to do an autopsy we could not get the stator out hub because the magnets were too strong.

We took both side panels off, rested it over a big enough hole and two of us pushed as hard as we could but could not push the stator out of the motor more than a 1/16th of inch or so.

Is there a trick?

I am going  to have to know it if I am going to rewind the 48V motor which, at the rate Golden Motor is responding to my warranty claims, maybe the fastest way to get on the road again.

Now I am wishing I had not tossed that old 36V wheel into the recycle bin last month , , , ,

[Leslie]

Put some good shoes and on and on a lounge or some padding in the area it will pop out and land, grab the magnet ring with both hands and push hard with your foot or both feet is better if you don't have clown feet.

It should land on something cosy about 3 feet from where you do it.  Dont be scared, just go for it.

[Leslie]

Updated:

I gots an old crappy 12v battery out and hooked it up between where the 3 phase wires are soldered together and each phase input individually and hung a spoon end over the slots and tested them all.

I  ended up with this WYE star configuration.

I drew this up because I am rewinding the motor sometime this week.

Almost done here.



One flavour could you do for me eclectrobent.

If you unwind the hub could you tell me how many turns are on each tooth of the 48v 1000 watt stator?

Thank you.

[Electrobent]

I am still hoping to get some sort of warranty coverage here!

Maybe I can tell how many turns there are just from taking a side panel off?

But after looking at your diagram I am thinking that maybe a worker missed the clockwise-counterclockwise distinction for one coil.

[Leslie]

I gots my high grade enamel copper and some off cut winding paper. $33 dollars so far.

The guys at HQ industrial windings have offered to dip this for $10 when I've finished

It very hard to get these windings off. Some drilling helps. 

Once I broke the first winding I knew then there was no turning back.

As you can see the plastic core insulator around the outside of the slots is melted from overheating.  I will remove this and replce it with the paper I got from HQ.

The grade of copper I got is rated above 180 deg and is darker in colour than the original copper.  The copper on this hub is about 5 shades darker than it was when the hub was new due to the excess heat from overloading the hub.

I havent got a good count of the turns yet but last count was 5t6p on the HBS36.  30 strands surround each tooth. I will get a certain on this before I finish.

Id say the 48v 1000 watts have 4t8p.  Im going to try for 5t7p as I want the power in the bottom end and a little bit less resistance if I can get the windings flat and ordered.

Ill see how I go.

[Leslie]

Oh dear I just finished removing the windings with a pile of utter destrucrion.  

The stator made it through the hard knocks with two teeth split on the ends just a little and I should be able to fix it back.

My hands are sore.

I still didnt manage to get a proper count on the windings on the account there are half turns and what I had to do to pry these windings from their old home.

I counted 7 turns on one and possibly 8.  Doing a test wind 8 is doable but 7 looks like the figure.  Ill do one phase with 6 turns 7 parallel and test the inductance and if I get more than 400uh this should do the job anyway.

Be nice if Tom could jump on about now and give me an idea.

EB if you plan on doing this set aside a good day or two for the work in completion.  Removing them is the hardest.

The more I took off it came exceedingly apparent the damage the heat had done to the outside insulation where they use plastic.  40% of this was melted away.  The paper in between the coils and stator was still in good shape and in good faith GM should observe this for future builds as indeed the paper out performs the plastic by a good margin.

[Bikemad]

The paper in between the coils and stator was still in good shape and in good faith GM should observe this for future builds as indeed the paper out performs the plastic by a good margin.

Leslie,

It might have something to do with a large metal stator, acting as a heat sink inside the windings, being considerably better at conducting and absorbing any excess heat than just air on the outer surfaces of the windings.

Alan
 

[Leslie]

The paper in between the coils and stator was still in good shape and in good faith GM should observe this for future builds as indeed the paper out performs the plastic by a good margin.

Leslie,

It might have something to do with a large metal stator, acting as a heat sink inside the windings, being considerably better at conducting and absorbing any excess heat than just air on the outer surfaces of the windings.

Alan
 

I'm not sure what you mean.

I see the stator getting very hot and the paper wrapped around the windings.


This is the result just the same.

Before and after shots.



This motor was pushed time and time again way past its intentional designed limits so in essence ive been very happy with it performance.  It was still functional before I undressed her but as you can see it was on its way to the grave.

IMO paper in place of the plastic mouldings would still be an improvement on the already hardy design.  I really wouldnt say what happened was due to a flaw in the design, not at all, I just I see room for better design.

GM should look at the data comming out of this work very closely because they will not find many GM motors that has been pushed so hard in such a way.

This damage has not been done by a 86v overvolt this has been done by sheer loading of weight by means of a trailer carrying lots of shopping.

[Leslie]

This is how I plan to tackle my problem.

Ive done a bit of restoration and removed the melted plastic stuff.

Another test wind with some lower temp WW4016 enamel magnet I have to experiment with and high temp winding paper cut into rectangles and folded into V's with with a 5mm nick in the middle to allow half flaps to overlap each other in the centre of each tooth.



This is a 7p 8 turn wind with flat layered incrementing winding style from top to bottom on the first coil. I am contemplating doing a 8p 7t.

I have a 1kg of higher grade enamel wire for the real job.  The guy I bought this off told me this redish enamel wire has a rating of 180 degrees 200 degree max.  So I am looking at making a better hub than it was.

I want some feedback from a few members here before I do anything. This does need its own thread.  

I shall succeed.

[Bikemad]

I don't know if this is any help:

http://www.mtmscientific.com/rewind.html

I know it's an alternator, but the principal is the same.

I particulary liked this bit:

Hand winding a stator is not especially difficult, and it only requires a few hours effort

Alan
 

[Leslie]

Thanks.  Good reading.

Ive been trying to read up as much as I can about this in order to learn more.  It would of been easier and I would advise most just to buy a new motor.

All of this has become a epic journey for me and I do enjoy the learning part of all this, not so much the work though.

Edit:

Ive started a thread on this as the topic subject is moving outside of coil inductance and EB's problem.

Here>>>>. http://goldenmotor.com/SMF/index.php?topic=1520.0